import Blender
from Blender import Draw, BGL

mystring = ""
mymsg = ""
toggle = 0

def event(evt, val):    # the function to handle input events
  global mystring, mymsg

  if not val:  # val = 0: it's a key/mbutton release
    if evt in [Draw.LEFTMOUSE, Draw.MIDDLEMOUSE, Draw.RIGHTMOUSE]:
      mymsg = "You released a mouse button."
      Draw.Redraw(1)
    return

  if evt == Draw.ESCKEY:
    Draw.Exit()                 # exit when user presses ESC
    return

  elif Draw.AKEY <= evt <= Draw.ZKEY: mystring += chr(evt)
  elif evt == Draw.SPACEKEY: mystring += ' '
  elif evt == Draw.BACKSPACEKEY and len(mystring):
    mystring = mystring[:-1]
  else: return # no need to redraw if nothing changed

  Draw.Redraw(1)

def button_event(evt):  # the function to handle Draw Button events
  global mymsg, toggle
  if evt == 1:
    mymsg = "You pressed the toggle button."
    toggle = 1 - toggle
    Draw.Redraw(1)

def gui():              # the function to draw the screen
  global mystring, mymsg, toggle
  if len(mystring) > 90: mystring = ""
  BGL.glClearColor(0,0,1,1)
  BGL.glClear(BGL.GL_COLOR_BUFFER_BIT)
  BGL.glColor3f(1,1,1)
  Draw.Toggle("Toggle", 1, 10, 10, 55, 20, toggle,"A toggle button")
  BGL.glRasterPos2i(72, 16)
  if toggle: toggle_state = "down"
  else: toggle_state = "up"
  Draw.Text("The toggle button is %s." % toggle_state, "small")
  BGL.glRasterPos2i(10, 230)
  Draw.Text("Type letters from a to z, ESC to leave.")
  BGL.glRasterPos2i(20, 200)
  Draw.Text(mystring)
  BGL.glColor3f(1,0.4,0.3)
  BGL.glRasterPos2i(340, 70)
  Draw.Text(mymsg, "tiny")

Draw.Register(gui, event, button_event)  # registering the 3 callbacks